WO2025184136A1

WO2025184136A1 - Cross-flow dialyzer

Info

Publication number: WO2025184136A1
Application number: PCT/US2025/017286
Authority: WO
Inventors: Michael Rocco; Pirouz DAEIHAGH
Original assignee: Wake Forest University Health Sciences
Current assignee: Wake Forest University Health Sciences
Priority date: 2024-02-27
Filing date: 2025-02-26
Publication date: 2025-09-04
Anticipated expiration: 2026-08-27

Abstract

A dialyzer may include a blood inlet and a clean blood outlet defining a blood flow path parallel to a longitudinal axis. A dialyzer may include a fresh dialysate inlet and a waste dialysate outlet defining a dialysate flow path oblique to the longitudinal axis.

Description

CROSS-FLOW DIALYZER

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 63/558469 filed on February 27, 2024, and of U.S. Provisional Patent Application No. 63/677830 filed on July 31 , 2024, the entire contents of which are incorporated herein by reference.

BACKGROUND

[0002] This disclosure relates to dialyzer devices used during hemodialysis. There are more than 450,000 patients with End-Stage Kidney Disease (ESKD) in the United States and more than 3 million patients globally who rely on lifesaving, three times weekly treatments with hemodialysis. A limitation of typical hemodialysis therapy is that it provides only about 10-15% of normal kidney function. Thus, the mortality rate for chronic hemodialysis patients in the United States is approximately 15% per year. This is a higher mortality rate than many cancers. The blood in a hemodialysis session is typically cleaned though a hollow fiber dialyzer. Diffusion across a dialysis membrane is the main mechanism for uremic toxin removal during a dialysis session. This process involves the movement of uremic molecules down their concentration gradient from the blood into a dialysate compartment of the dialyzer. The diffusion gradient remains a pivotal factor in providing efficient clearance of toxins during a dialysis session. A typical dialyzer filter casing provides counter-current flow of the blood and dialysate along the length of the dialyzer in respective compartments of the dialyzer. Rapid dissipation of this gradient along the dialyzer length contributes to a relatively low efficiency of each dialysis session.

SUMMARY

[0003] In some aspects, the techniques described herein relate to a dialyzer including: a blood inlet and a clean blood outlet defining a blood flow path parallel to a longitudinal axis; and a fresh dialysate inlet and a waste dialysate outlet defining a dialysate flow path oblique to the longitudinal axis.

[0004] In some aspects, the techniques described herein relate to a dialyzer, wherein the blood inlet and the clean blood outlet are configured to hold a semipermeable membrane therebetween.

[0005] In some aspects, the techniques described herein relate to a dialyzer, further including a semipermeable membrane positioned between the blood inlet and the clean blood outlet. [0006] In some aspects, the techniques described herein relate to a dialyzer, wherein the semipermeable membrane includes a plurality of hollow fibers.

[0007] In some aspects, the techniques described herein relate to a dialyzer, wherein the semipermeable membrane defines a square cross-sectional profile perpendicular to the longitudinal axis.

[0008] In some aspects, the techniques described herein relate to a dialyzer, wherein the semipermeable membrane defines a circular cross-sectional profile perpendicular to the longitudinal axis.

[0009] In some aspects, the techniques described herein relate to a dialyzer, wherein the blood inlet and the clean blood outlet define a membrane length therebetween parallel to the longitudinal axis, and wherein the fresh dialysate inlet includes a fresh dialysate chamber dispersing the flow of dialysate across the membrane length.

[0010] In some aspects, the techniques described herein relate to a dialyzer, wherein the blood inlet and the clean blood outlet define a membrane length therebetween parallel to the longitudinal axis, and wherein the fresh dialysate inlet includes a fresh dialysate chamber defining a chamber width equal to the membrane length.

[0011] In some aspects, the techniques described herein relate to a dialyzer, further including a plurality of inlet baffles positioned within the fresh dialysate chamber.

[0012] In some aspects, the techniques described herein relate to a dialyzer, wherein the plurality of inlet baffles distribute the flow of dialysate across the membrane length.

[0013] In some aspects, the techniques described herein relate to a dialyzer, wherein the blood inlet and the clean blood outlet are coaxial with the longitudinal axis.

[0014] In some aspects, the techniques described herein relate to a dialyzer, wherein the fresh dialysate inlet and the waste dialysate outlet are coaxial and perpendicular to the longitudinal axis.

[0015] In some aspects, the techniques described herein relate to a dialyzer, wherein the blood inlet includes a blood inlet chamber, wherein the clean blood outlet includes a blood outlet chamber, and wherein the blood inlet chamber and the blood outlet chamber are spaced apart by a membrane length.

[0016] In some aspects, the techniques described herein relate to a dialyzer, wherein the fresh dialysate inlet includes a fresh dialysate chamber, and wherein the waste dialysate outlet includes a waste dialysate chamber.

[0017] In some aspects, the techniques described herein relate to a dialyzer, wherein the blood inlet, the clean blood outlet, the fresh dialysate inlet, and the waste dialysate outlet are formed as a single piece.

[0018] In some aspects, the techniques described herein relate to a dialyzer including: a blood inlet; a clean blood outlet spaced apart from the blood inlet and configured to maintain a semipermeable membrane therebetween, the blood inlet and the clean blood outlet defining a longitudinal axis; a fresh dialysate inlet configured to provide a flow of dialysate across the semipermeable membrane in a direction perpendicular to the longitudinal axis; and a waste dialysate outlet spaced apart from the fresh dialysate inlet and configured to receive the flow of dialysate in the direction perpendicular to the longitudinal axis.

[0019] In some aspects, the techniques described herein relate to a dialyzer, wherein the blood inlet includes a blood inlet chamber, wherein the clean blood outlet includes a blood outlet chamber, and wherein the blood inlet chamber is spaced apart from the blood outlet chamber by a membrane length parallel to the longitudinal axis.

[0020] In some aspects, the techniques described herein relate to a dialyzer, wherein the fresh dialysate inlet includes a fresh dialysate chamber, wherein the waste dialysate outlet includes a waste dialysate chamber, and wherein the fresh dialysate chamber and the waste dialysate chamber define a dialysate width equal to the membrane length.

[0021] In some aspects, the techniques described herein relate to a dialyzer including: a blood inlet configured to receive patient blood; a blood inlet chamber coupled to the blood inlet and configured to receive the patient blood from the blood inlet; a semipermeable membrane coupled to the blood inlet chamber and defining a longitudinal axis and a membrane length parallel to the longitudinal axis, the semipermeable membrane configured to receive the patient blood from the blood inlet chamber; a blood outlet chamber coupled to the semipermeable membrane and configured to receive cleaned patient blood from the semipermeable membrane; a clean blood outlet coupled to the blood outlet chamber and configured to expel the cleaned patient blood from the dialyzer; a fresh dialysate inlet configured to receive fresh dialysate; a fresh dialysate chamber configured to receive the fresh dialysate from the fresh dialysate inlet and distribute the fresh dialysate across the membrane length in a direction perpendicular to the longitudinal axis; a waste dialysate chamber configured to receive waste dialysate from the semipermeable membrane across the membrane length in the direction perpendicular to the longitudinal axis; and a waste dialysate outlet configured to receive the waste dialysate from the waste dialysate chamber and expel the waste dialysate from the dialyzer.

[0022] In some aspects, the techniques described herein relate to a dialyzer, further including: a plurality of inlet baffles positioned within the fresh dialysate chamber to distribute the fresh dialysate across the membrane length; and a plurality of outlet baffles positioned within the waste dialysate chamber to receive the waste dialysate from across the membrane length.

[0023] This summary is illustrative only and is not intended to be in any way limiting. Other aspects, inventive features, and advantages of the devices or processes described herein will become apparent in the detailed description set forth herein, taken in conjunction with the accompanying figures, wherein like reference numerals refer to like elements.

BRIEF DESCRIPTION OF DRAWINGS

[0024] The device is explained in even greater detail in the following drawings. The drawings are merely exemplary and certain features may be used singularly or in combination with other features. The drawings are not necessarily drawn to scale.

[0025] FIG. 1 is a schematic representation of a dialyzer, according to some implementations.

[0026] FIG. 2 is a perspective view of a dialyzer, according to some implementations.

[0027] FIG. 3 is a sectional view of the dialyzer of FIG. 2.

[0028] FIG. 4 is a perspective view of a dialyzer, according to some implementations.

[0029] FIG. 5 is a sectional view of the dialyzer of FIG. 4.

[0030] FIG. 6 is a perspective view of a dialyzer, according to some implementations. [0031] FIG. 7 is a sectional view of the dialyzer of FIG. 6.

[0032] FIG. 8 is a perspective view of a dialyzer, according to some implementations.

[0033] FIG. 9 is a sectional view of the dialyzer of FIG. 8.

[0034] FIG. 10 is a perspective view of a dialyzer, according to some implementations.

[0035] FIG. 11 is a sectional view of the dialyzer of FIG. 10.

[0036] FIG. 12 is a perspective view of a dialyzer, according to some implementations.

[0037] FIG. 13 is a sectional view of the dialyzer of FIG. 12.

[0038] FIG. 14 is a perspective view of a dialyzer, according to some implementations.

[0039] FIG. 15 is a front view of the dialyzer of FIG. 14.

[0040] FIG. 16 is a side view of the dialyzer of FIG. 14.

[0041] FIG. 17 is a top view of the dialyzer of FIG. 14.

[0042] FIG. 18 is a perspective view of the dialyzer of FIG. 14.

[0043] FIG. 19 is a perspective view of a dialyzer, according to some implementations.

[0044] FIGS. 20-28 show another exemplary dialyzer, according to some implementations.

[0045] FIGS. 29-35 show another exemplary dialyzer, according to some implementations.

[0046] FIGS. 36-43 show results of experiments conducted to compare two prototype dialyzers constructed according to this disclosure and a commercially available dialyzer (e.g., the Fresenius F180NRe dialyzer) as well as with comparisons with published clearance data from Fresenius dialyzers, according to some implementations.

DETAILED DESCRIPTION

[0047] Following below are more detailed descriptions of concepts related to, and implementations of, methods, apparatuses, and systems for a dialyzer used in hemodialysis. The figures illustrate exemplary implementations in detail and the present disclosure is not limited to the details or methodology set forth in the description or illustrated in the figures. The terminology used herein is for the purpose of description only and should not be regarded as limiting.

[0048] Referring to the figures generally, the various implementations disclosed herein relate to systems, apparatuses, and methods for a new dialyzer whereby the diffusion gradient is more robustly maintained throughout an entire length of the dialyzer. The new dialyzer provides a crossflow design that allows fresh dialysate to come in contact with hollow fibers along a full length of the dialyzer via cross flow (i.e., across the long axis of the dialyzer) as opposed to the typical counter-current flow (i.e., parallel to the long axis of the dialyzer). In vitro data for one such implementation of the new dialyzer in comparison with the Fresenius 180NRe dialyzer, as well as with published clearance data from Fresenius dialyzers is provided in FIGS 36-43 and paragraphs [0068-0069]. Improved clearance of uremic molecules provided by the cross-flow dialyzer should provide significant improvement in patient morbidity and mortality without an increase in cost.

[0049] As shown in FIG. 1, a dialyzer 20 includes a blood inlet 24 that receives blood from a patient’s body (e.g., from a peristaltic blood pump), a clean blood outlet 28 that provides clean blood from the dialyzer 20 (e.g., for return to the patient’s body), and a semipermeable membrane 32 held between the blood inlet 24 and the clean blood outlet 28 and including a large number of hollow fibers through which the blood flows along a blood flow path 34 from the blood inlet 24 to the clean blood outlet 28. In some implementations, the hollow fibers are embedded on the inlet side and the outlet side in a potting compound. In some implementations, the semipermeable membranes 32 includes hollow fibers formed from unmodified cellulose, modified/regenerated cellulose and synthetic membranes (e.g., cellulose acetate, polysulfone, polycarbonate, polyamide, polyacrylonitrile (PAN) and poly acryl-poly amide acrylate (PMMA)). The dialyzer 20 also includes a fresh dialysate inlet 36 that receives fresh dialysate and a waste dialysate outlet 40 that expels waste dialysate that has absorbed waste from the patient’s blood via the semipermeable membrane 32. A dialysate flow path 42 is defined between the fresh dialysate inlet 36 and the waste dialysate outlet 40.

[0050] The blood inlet 24 includes a blood inlet chamber 44 that receives a flow of blood from the blood inlet 24 and allows for even pressure distribution across the semipermeable membrane 32. The clean blood outlet 28 includes a blood outlet chamber 48 that collects clean blood from the semipermeable membrane 32 before the cleaned blood exits the dialyzer 20 via the clean blood outlet 28. [0051] The semipermeable membrane 32 defines a longitudinal axis 52 and a membrane length 56 along the longitudinal axis 52. The hollow fibers extend generally along the longitudinal axis 52 from the blood inlet chamber 44 to the blood outlet chamber 48. In some implementations, the semipermeable membrane 32 defines a square cross sectional profile perpendicular to the longitudinal axis 52. In some implementations, the semipermeable membrane 32 defines a circular, rectangular, ovoid, octagonal, or any other geometrical shape cross sectional profile perpendicular to the longitudinal axis 52. In some implementations, the blood inlet chamber 44 is spaced apart from the blood outlet chamber 48 by the membrane length 56 parallel to the longitudinal axis 52.

[0052] The fresh dialysate inlet 36 includes a fresh dialysate chamber 60 that receives a flow of fresh dialysate and distributes the dialysate across the membrane length 56 of the semipermeable membrane 32. In some implementations, the shape of the fresh dialysate chamber 60 is different. In some implementations, the fresh dialysate inlet 36 includes inlet baffles 64 that aid in the even distribution of flow and pressure of the dialysate within the fresh dialysate chamber 60 across the membrane length 56. Seven inlet baffles 64 are shown in FIG. 1. In some implementations, more than seven or less than seven inlet baffles 64 can be included. In some implementations, the inlet baffles 64 are eliminated. In some implementations, the inlet baffles 64 are shaped differently.

[0053] The waste dialysate outlet 40 includes a waste dialysate chamber 68 that receives a flow of waste dialysate that has passed through the semipermeable membrane 32 and provides a balanced flow and pressure of the waste dialysate exiting the semipermeable membrane 32. In some implementations, the shape of the waste dialysate chamber 68 is different. In some implementations, the waste dialysate outlet 40 includes outlet baffles 72 that aid in the even distribution of flow and pressure of the dialysate within the waste dialysate chamber 68 across the membrane length 56. Seven outlet baffles 72 are shown in FIG. 1. In some implementations, more than seven or less than seven outlet baffles 72 can be included. In some implementations, the outlet baffles 72 are eliminated. In some implementations, the outlet baffles 72 are shaped differently.

[0054] In some implementations, the flow of dialysate is a cross-flow that flows generally in a direction oblique to the longitudinal axis 52. For example, the cross-flow can run perpendicular to the longitudinal axis 52. In some implementations, the fresh dialysate inlet 36 and the waste dialysate outlet 40 are coaxial and perpendicular to the longitudinal axis 52. In some implementations, the flow of dialysate flows generally at an angle of more than 45 degrees relative to the longitudinal axis 52. In some implementations, the fresh dialysate chamber 60 and the waste dialysate chamber 68 define a dialysate flow width that is equal to the membrane length.

[0055] In operation, the dialyzer 20 receives a flow of patient blood into the blood inlet 24. The patient blood flows into the blood inlet chamber 44, through the semipermeable membrane 32 along the blood flow path 34, collects in the blood outlet chamber 48, and exits the dialyzer 20 through the clean blood outlet 28. The patient’s blood flows generally in a direction from the blood inlet 24 to the clean blood outlet 28 parallel to the longitudinal axis 52 across the membrane length 56. Clean or fresh dialysate is pumped from the fresh dialysate inlet 36 to the waste dialysate outlet 40 through the semipermeable membrane 32. For example, when the semipermeable membrane 32 includes hollow fibers, the patient’s blood is pumped through the center of each of the hollow fibers, and the dialysate flows around the exterior of the hollow fibers. As the dialysate flows over the semipermeable membrane 32, contaminants are released in the dialysate from the patient’s blood through the semipermeable membrane 32 such that waste dialysate (i.e., dialysate that includes waste products absorbed via the semipermeable membrane 32) is expelled from the waste dialysate outlet 40.

[0056] The structure and operation of the dialyzer 20 maintains a robust diffusion gradient along the entire membrane length 56 of the hollow fibers of the semipermeable membrane 32. The dialyzer 20 provides significantly more efficient clearance of toxins from the patient’s blood in comparison to typical counter-current dialysis whereby the diffusion gradient is rapidly dissipated along the length of the fibers. The relative constant gradient along the membrane length 56 of the semipermeable membrane 32 allows for significantly improved toxin clearance from blood resulting in reduction in uremic toxins concentration in patient’s body, and significantly improved efficiency when compared to typical dialyzers at lower blood and dialysate flow rates. In vitro testing of one implementation of the new dialyzer in comparison with the Fresenius 180NRe dialyzer, as well as with comparisons with published clearance data from Fresenius dialyzers, as shown in FIGS 36-43 and paragraphs [0068-0069], demonstrated that the same clearance could be achieved by the dialyzer 20 when compared to a typical countercurrent dialyzer at the same blood and dialysate flow rates while using a significantly lesser number of hollow fibers. In other words, similar clearance was achieved using a smaller surface area dialyzer. The semipermeable membrane 32 made of hollow fibers is a high cost item of the dialyzer 20 and fewer fibers lowers the cost to make the dialyzer 20 compared to typical counterflow dialyzers. The dialyzer 20 utilizes cross flow and can provide a high clearance of toxins at lower flow rates of both blood and dialysate when compared to typical counter-flow dialyzers.

[0057] FIGS. 2-18 show alternative dialyzers according to some implementations. In FIGS. 2- 13, the dialyzers are shown without the blood inlet 24 and the clean blood outlet 28 for clarity of viewing the fresh dialysate chamber 60 and the waste dialysate chamber 68.

[0058] As shown in FIGS. 2 and 3, a dialyzer 120 is similar to the dialyzer 20 discussed above and is numbered with like reference numerals in the 100 series. The semipermeable membrane 132 defines a round cross-sectional profile. The fresh dialysate chamber 160 and the waste dialysate chamber 168 are sized so that a ninety degree (90°) radial segment of the semipermeable membrane 132 is exposed to the interior of the fresh dialysate chamber 160 and the waste dialysate chamber 168.

[0059] As shown in FIGS. 4 and 5, a dialyzer 220 is similar to the dialyzer 20 discussed above and is numbered with like reference numerals in the 200 series. The semipermeable membrane 232 defines a round cross-sectional profile. The fresh dialysate chamber 260 and the waste dialysate chamber 268 are sized so that a sixty degree (60°) radial segment of the semipermeable membrane 232 is exposed to the interior of the fresh dialysate chamber 260 and the waste dialysate chamber 268.

[0060] As shown in FIGS. 6 and 7, a dialyzer 320 is similar to the dialyzer 20 discussed above and is numbered with like reference numerals in the 300 series. The semipermeable membrane 332 defines a round cross-sectional profile. The fresh dialysate chamber 360 and the waste dialysate chamber 368 are sized so that a thirty-five degree (35°) radial segment of the semipermeable membrane 332 is exposed to the interior of the fresh dialysate chamber 360 and the waste dialysate chamber 368.

[0061] As shown in FIGS. 8 and 9, a dialyzer 420 is similar to the dialyzer 20 discussed above and is numbered with like reference numerals in the 400 series. The fresh dialysate chamber 460 and the waste dialysate chamber 468 extend along the longitudinal axis 452 and define a constant cross-sectional profile in a direction perpendicular to the longitudinal axis 452 along the membrane length 456. The fresh dialysate chamber 460 and the waste dialysate chamber 468 are in direct communication over a ninety degree (90°) radial segment of the semipermeable membrane 632. [0062] As shown in FIGS. 10 and 11 , a dialyzer 520 is similar to the dialyzer 420 discussed above and is numbered with like reference numerals in the 500 series. The fresh dialysate chamber 560 and the waste dialysate chamber 568 define a smaller volume than the fresh dialysate chamber 460 and waste dialysate chamber 468 discussed above with respect to the dialyzer 420. The fresh dialysate chamber 560 and the waste dialysate chamber 568 are in direct communication over a sixty degree (60°) radial segment of the semipermeable membrane 632.

[0063] As shown in FIGS. 12 and 13, a dialyzer 620 is similar to the dialyzer 420 discussed above and is numbered with like reference numerals in the 600 series. The fresh dialysate chamber 660 and the waste dialysate chamber 668 define a smaller volume than the fresh dialysate chamber 460 and waste dialysate chamber 468 discussed above with respect to the dialyzer 420. The fresh dialysate chamber 660 and the waste dialysate chamber 668 are in direct communication over a thirty-five degree (35°) radial segment of the semipermeable membrane 632.

[0064] As shown in FIGS 14-18, a dialyzer 720 is similar to the dialyzer 20 discussed above and is numbered with like reference numerals in the 700 series. The dialyzer 720 is produced using injection molding and is structured to receive a semipermeable membrane 732 that defines a circular-shape cross section (taken in a direction perpendicular to the longitudinal axis 752). The dialyzer 720 includes eighteen inlet baffles 764 and eighteen outlet baffles 772.

[0065] As used herein, the semipermeable membrane 32 refers to an assembly or system that can contain one or more filter media or semipermeable membranes. For example, the semipermeable membrane 32 discussed above includes a large number of hollow fibers connected together at opposing ends to form the semipermeable membrane 32. Dialyzers discussed herein can be used with circular or any other geometrical shape semipermeable membrane 32 or square or any other geometrical design semipermeable membrane 32. That is to say, the ends of the semipermeable membrane 32 that engage with the dialyzer 20 at the inlet 24 and the outlet 28 can be square, circular, or another shape. Additionally, the cross-sectional profile of the semipermeable membrane 32 can be made up of hollow fibers packed into a generally square shape, a generally circular shape, a rectangular shape, or another shape, as desired. In some implementations, a square semipermeable membrane 32 allows for more even and efficient flow of dialysate through the semipermeable membrane 32 and can improve overall efficiency of clearance of toxins. [0066] FIG. 19 shows a dialyzer configured to receive a square shaped semipermeable membrane, including inlet baffles and no outlet baffles.

[0067] FIGS. 20-28 show a dialyzer configured to receive a square shaped semipermeable membrane and including a cage or lattice structure that can support the semipermeable membrane during operation.

[0068] FIGS. 29-35 show another dialyzer configured to receive a square shaped semipermeable membrane.

EXAMPLES

[0069] Two prototypes were made according to the above disclosure and tested in comparison to the commercially available Fresenius 180NRE dialyzer as well as compared with published clearances of commercially available Fresenius dialyzers. As shown in FIGS. 36-43, the prototype dialyzers performed very well when compared to, the Fresenius F180NRe dialyzer and with the published clearances of Fresenius dialyzers For all the experiments run and visualized in FIGS. 36-43 in vitro analysis was performed using Association for the Advancement of Medical Instrumentation® (AAMI) standards with samples taken after a 10-minute equilibration period, five samples taken over 20 minutes, and results averaged in each graph. The findings of the experiments are summarized in the following tables.

Table 1 - Surface area and priming volume of prototypes Table 2 - Normalized clearance data

[0070] The prototype dialyzers are markedly more efficient than conventional dialyzers when measured by clearance normalized by surface area in meter squared. Despite the prototype dialyzers having both a surface area and priming volume less than 50% of the control dialyzer, the clearances approach that of a Fresenius Fl 80 dialyzer.

[0071] For purposes of this description, certain advantages and novel features of the aspects and configurations of this disclosure are described herein. The described methods, systems, and apparatus should not be construed as limiting in any way. Instead, the present disclosure is directed toward all novel and nonobvious features and aspects of the various disclosed aspects, alone and in various combinations and sub-combinations with one another. The disclosed methods, systems, and apparatus are not limited to any specific aspect, feature, or combination thereof, nor do the disclosed methods, systems, and apparatus require that any one or more specific advantages be present or problems be solved.

[0072] Although the description may discuss a specific order of method steps, the order of such steps may differ from what is depicted and described, unless specified differently above. Also, two or more steps may be performed concurrently or with partial concurrence, unless specified differently above. Such variation may depend, for example, on the software and hardware systems chosen and on designer choice. All such variations are within the scope of the disclosure. Likewise, software implementations of the described methods could be accomplished with standard programming techniques with rule-based logic and other logic to accomplish the various connection steps, processing steps, comparison steps, and decision steps.

[0073] Features disclosed in this specification (including any accompanying claims, abstract, and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The claimed features extend to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract, and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

[0074] As used in the specification and the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from “about” one particular value, and/or to “about” another particular value. When such a range is expressed, another aspect includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about”, it will be understood that the particular value forms another aspect. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint. The terms “about” and “approximately” are defined as being “close to” as understood by one of ordinary skill in the art. In one non-limiting aspect the terms are defined to be within 10%. In another non-limiting aspect, the terms are defined to be within 5%. In still another non-limiting aspect, the terms are defined to be within 1%.

[0075] The terms “coupled”, “connected”, and the like as used herein mean the joining of two members directly or indirectly to one another. Such joining may be stationary (e.g., permanent) or moveable (e.g., removable or releasable). Such joining may be achieved with the two members or the two members and any additional intermediate members being integrally formed as a single unitary body with one another or with the two members or the two members and any additional intermediate members being attached to one another. If “coupled” or variations thereof are modified by an additional term (e.g., directly coupled), the generic definition of “coupled” provided above is modified by the plain language meaning of the additional term (e.g., “directly coupled” means the joining of two members without any separate intervening member), resulting in a narrower definition than the generic definition of “coupled” provided above. Such coupling may be mechanical, electrical, or fluidic.

[0076] Certain terminology is used in the following description for convenience only and is not limiting. The words “right”, “left”, “lower”, and “upper” designate direction in the drawings to which reference is made. The words “inner” and “outer” refer to directions toward and away from, respectively, the geometric center of the described feature or device. The words “distal” and “proximal” refer to directions taken in context of the item described and, with regard to the instruments herein described, are typically based on the perspective of the practitioner using such instrument, with “proximal” indicating a position closer to the practitioner and “distal” indicating a position further from the practitioner. The terminology includes the above-listed words, derivatives thereof, and words of similar import.

[0077] Throughout the description and claims of this specification, the word “comprise” and variations of the word, such as “comprising” and “comprises”, means “including but not limited to”, and is not intended to exclude, for example, other additives, components, integers or steps. “Exemplary” means “an example of’ and is not intended to convey an indication of a preferred or ideal aspect. “Such as” is not used in a restrictive sense, but for explanatory purposes.

[0078] The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present invention has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention.

Claims

What is claimed is:

1. A dialyzer comprising: a blood inlet and a clean blood outlet defining a blood flow path parallel to a longitudinal axis; and a fresh dialysate inlet and a waste dialysate outlet defining a dialysate flow path oblique to the longitudinal axis.

2. The dialyzer of claim 1, wherein the blood inlet and the clean blood outlet are configured to hold a semipermeable membrane therebetween.

3. The dialyzer of claim 1, further comprising a semipermeable membrane positioned between the blood inlet and the clean blood outlet.

4. The dialyzer of claim 2, wherein the semipermeable membrane includes a plurality of hollow fibers.

5. The dialyzer of claim 2, wherein the semipermeable membrane defines a square cross- sectional profile perpendicular to the longitudinal axis.

6. The dialyzer of claim 2, wherein the semipermeable membrane defines a circular cross- sectional profile perpendicular to the longitudinal axis.

7. The dialyzer of claim 1, wherein the blood inlet and the clean blood outlet define a membrane length therebetween parallel to the longitudinal axis, and wherein the fresh dialysate inlet includes a fresh dialysate chamber dispersing a flow of dialysate along the membrane length.

8. The dialyzer of claim 1, wherein the blood inlet and the clean blood outlet define a membrane length therebetween parallel to the longitudinal axis, and wherein the fresh dialysate inlet includes a fresh dialysate chamber defining a chamber width equal to the membrane length.

9. The dialyzer of claim 8, further comprising a plurality of inlet baffles positioned within the fresh dialysate chamber.

10. The dialyzer of claim 9, wherein the plurality of inlet baffles distribute a flow of dialysate across the membrane length.

11. The dialyzer of claim 1, wherein the blood inlet and the clean blood outlet are coaxial with the longitudinal axis.

12. The dialyzer of claim 1, wherein the fresh dialysate inlet and the waste dialysate outlet are coaxial and perpendicular to the longitudinal axis.

13. The dialyzer of claim 1, wherein the blood inlet includes a blood inlet chamber, wherein the clean blood outlet includes a blood outlet chamber, and wherein the blood inlet chamber and the blood outlet chamber are spaced apart by a membrane length.

14. The dialyzer of claim 1, wherein the fresh dialysate inlet includes a fresh dialysate chamber, and wherein the waste dialysate outlet includes a waste dialysate chamber.

15. The dialyzer of claim 1, wherein the blood inlet, the clean blood outlet, the fresh dialysate inlet, and the waste dialysate outlet are formed as a single piece.

16. A dialyzer comprising: a blood inlet; a clean blood outlet spaced apart from the blood inlet and configured to maintain a semipermeable membrane therebetween, the blood inlet and the clean blood outlet defining a longitudinal axis; a fresh dialysate inlet configured to provide a flow of dialysate across the semipermeable membrane in a direction perpendicular to the longitudinal axis; and a waste dialysate outlet spaced apart from the fresh dialysate inlet and configured to receive the flow of dialysate in the direction perpendicular to the longitudinal axis.

17. The dialyzer of claim 16, wherein the blood inlet includes a blood inlet chamber, wherein the clean blood outlet includes a blood outlet chamber, and wherein the blood inlet chamber is spaced apart from the blood outlet chamber by a membrane length parallel to the longitudinal axis.

18. The dialyzer of claim 17, wherein the fresh dialysate inlet includes a fresh dialysate chamber, wherein the waste dialysate outlet includes a waste dialysate chamber, and wherein the fresh dialysate chamber and the waste dialysate chamber define a dialysate width equal to the membrane length.

19. A dialyzer comprising: a blood inlet configured to receive patient blood; a blood inlet chamber coupled to the blood inlet and configured to receive the patient blood from the blood inlet; a semipermeable membrane coupled to the blood inlet chamber and defining a longitudinal axis and a membrane length parallel to the longitudinal axis, the semipermeable membrane configured to receive the patient blood from the blood inlet chamber; a blood outlet chamber coupled to the semipermeable membrane and configured to receive cleaned patient blood from the semipermeable membrane; a clean blood outlet coupled to the blood outlet chamber and configured to expel the cleaned patient blood from the dialyzer; a fresh dialysate inlet configured to receive fresh dialysate; a fresh dialysate chamber configured to receive the fresh dialysate from the fresh dialysate inlet and distribute the fresh dialysate across the membrane length in a direction perpendicular to the longitudinal axis; a waste dialysate chamber configured to receive waste dialysate from the semipermeable membrane across the membrane length in the direction perpendicular to the longitudinal axis; and a waste dialysate outlet configured to receive the waste dialysate from the waste dialysate chamber and expel the waste dialysate from the dialyzer.

20. The dialyzer of claim 19, further comprising: a plurality of inlet baffles positioned within the fresh dialysate chamber to distribute the fresh dialysate across the membrane length; and a plurality of outlet baffles positioned within the waste dialysate chamber to receive the waste dialysate from across the membrane length.